Beat summer heat with…ice

Written by erik


As the temperature across the country begins to climb into prime air conditioning territory, building managers are preparing to crank up their commercial HVAC units. Because daily temperature peaks tend to coincide with daily electricity usage peaks, air conditioners put an especially heavy strain on the electrical grid. The folks at Ice Energy have a clever way to shift power needs to off-peak hours, using nothing but water and ingenuity.

The basic idea is simple — use off-peak electricity to freeze water around copper tubing containing refrigerant, insulate it very well, and release it into the HVAC system once the daytime temperature starts to rise and office workers need relief. The HVAC compressor doesn’t even need to get turned on, since the cooling is all being done by the big block of ice left over from the night before. So energy use during peak hours can fall up to 95% according to the company. (Your mileage may vary — we haven’t field tested this at TerraPass world HQ.)

Why does this matter if the building still has to use energy to make the ice in the first place?

First, the system overall uses less energy than a conventional HVAC system does for a small- to medium-sized commercial installation. Though the compressor does need to run to make the ice, making the total electricity consumed about the same as a regular system, there is up to 30% less loss in transmission off-peak (because line loss varies with the square of the current carried in the line).

Second, the shift to off-peak power consumption means that there is less stress on the electrical grid during the day, which in turns means local utilities don’t need to fire up incremental generating facilities. That in turn means lower overall carbon emissions, since those incremental facilities are often older and dirtier than base load power generation facilities are.

Third, off peak power is a whole lot cheaper, leaving building owners and tenants with extra money to spend on efficiency measures like double-paned windows and better insulation.

Ice — it’s not just for making hand-cranked margaritas anymore.

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  1. Tom Harrison

    We talk a lot about the Smart Grid and renewable energy. All good. We also talk about reducing consumption, which is frequently lumped into “efficiency”. All good.
    There should be a new category called “&@%!$ Common Sense” (FCS, for short, perhaps), that we seem to overlook in our desire to find magic bullets and other kinds of magic to solve our energy issues. FCS dictates that we find the simple solutions first, and that we do dull, uninspiring things like buy power off-peak.
    Naturally, of course, FCS will only be done by the Dutch, and other Europeans, and then derided by us inventive Americans as boring.
    The opportunity to reduce our consumption through means both clever and dull are our most accessible, immediate, lowest cost options.

  2. BCC

    Ice energy isn’t a huge environmental win, but it is FCS (to use Tom’s terminology).
    It also is an energy storage device, of sorts. Energy storage devices are good enabling technologies for renewable energy, especially wind.
    So, the better we get at implementing cost-effective energy storage devices like ice storage, the easier it will be to integrate large-scale variable production renewables into the grid.

  3. Geoff G.

    …except it’s still using electricity – “Off-Peak” electricity. Is that better for the environment, or better for the electric grid and wallet. Off peak in many regions may be dirtiest electricity is made. It may be less strain on the grid, but its still a strain on the environment. Read More From NPR: Richard Harris
    “In some cases, people use not only more energy, but dirtier energy, too. That’s because in some parts of the country, nighttime electricity often comes from coal-fired power plants. They’re usually the cheapest source, so they are used first. When demand is higher during the day, the additional electricity is more likely to come from cleaner natural gas. So in parts of the country that rely heavily on coal power, nighttime energy means dirtier energy.”

  4. Owen

    There is another potential positive for the environment: night is typically cooler than day, so less energy is needed to cool at night, even if the shift in temperature is only a few degrees.
    I do not know whether this advantage is countered by the inefficiency of the storage process.

  5. Adam Stein

    Yeah, this is cool technology. Some more info:
    Tom and BCC — agree that this is common sense, and I think it actually counts as smart grid as well. Although we didn’t get into this in the blog post, I’m pretty sure that Ice Energy has embedded a lot of controls in the units that allow utilities to do demand management.
    Geoff G. — off-peak electricity is generally better for the environment because a lot of that coal would be burned anyway — the generators don’t get shut down at night, and instead the electricity just goes to waste. Further, this sort of demand shifting is an enabler for renewable energy. Wind turbines, for example, often spin more at night, but the cooling load occurs during the day. Storage devices like the Ice Technology allow that load to be shifted around, so that wind can be more easily integrated into the grid.
    Owen — yes, this is true. A lot less energy is required to cool the water at night. It really is a very simple and nifty piece of technology.

  6. Sue | Air Conditioning

    This is a very interesting piece of technology, and Owen is correct in stating that the nights are a little less cooler than that of the day, but for me if the nights are really that much cooler at night why is that I find it harder to sleep?? Strange but true.